Python: how do I format a number with commas / as currency / percentage?

Question

I want '1,234,567', '$1,234.50', and '12.3%' from raw numbers. What's the clean f-string syntax?

IT-QA Assistant · Accepted Answer

*AI-drafted answer — reviewed for correctness. Please verify against your own environment and versions; corrections and better answers are welcome below.*

f-string format specs handle all of these:

```python
n = 1234567
price = 1234.5
ratio = 0.123

f"{n:,}"        # '1,234,567'   thousands separator
f"{price:,.2f}"  # '1,234.50'    2 decimals + commas
f"${price:,.2f}" # '$1,234.50'
f"{ratio:.1%}"   # '12.3%'       % multiplies by 100 and adds sign
f"{n:_}"        # '1_234_567'   underscore separator
f"{42:05d}"      # '00042'       zero-pad to width 5
f"{255:x}"       # 'ff'          hex
```

The grammar is `{value:[fill][align][sign][width][,][.precision][type]}`. For locale-aware currency/grouping (correct symbol and separators per region), use the `babel` library or `locale.currency()` rather than hardcoding `$` and commas.

Python: how do I format a number with commas / as currency / percentage?

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